A method for preparing a core-shell structured Ni@Ni3S2 catalyst for electro-oxidation of 5-hydroxymethylfurfural on a gram scale and its application

Abstract

The present invention discloses a method for preparing a core-shell structure Ni@Ni3S2 catalyst for electro-oxidation of 5-hydroxymethylfurfural on a gram scale and its application. This method can prepare a nickel-based electro-oxidation HMF catalyst on a gram scale or above by immersing nickel powder in a sodium sulfide solution at room temperature. The generated Ni3S2 active layer shell has a nanoflower-like structure, which can expose abundant active sites. The cooperation between the active layer shell and the metallic nickel core helps the highly selective oxidation of HMF to produce FDCA. This method has prominent advantages such as simple and easy operation, enabling mass production above the gram scale, high controllability, low energy consumption, and low cost. The prepared catalyst has high catalytic activity and high FDCA selectivity, and is cheap and easily available, and can promote the efficient oxidation of HMF to prepare FDCA under mild conditions.

Description

Technical Field

[0001] The present invention belongs to the technical field of catalysts for electro - oxidizing 5 - hydroxymethylfurfural (HMF) to synthesize 2,5 - furandicarboxylic acid (FDCA), and particularly relates to a method for preparing a core - shell structure Ni@Ni3S2 catalyst for electro - oxidizing 5 - hydroxymethylfurfural on a gram scale and its application. Background Art

[0002] As an organic carbon resource, biomass has the characteristics of renewable energy and can be used to synthesize biodegradable biomass - based materials to replace traditional petroleum - based materials. 2,5 - Furandicarboxylic acid (FDCA), as one of the most important compounds in the biomass family, its derivatives are widely used in chemical industry, medicine, etc. For example, polyethylene furanate can replace polyethylene terephthalate plastic, thus reducing the use of petroleum - based chemicals.

[0003] At present, the preparation methods of FDCA can be divided into three categories: 5 - hydroxymethylfurfural (HMF) oxidation method, furan compound conversion method and sugar acid dehydration method. Among them, the reaction path of the HMF oxidation method does not involve the cleavage or addition of C - C bonds and can obtain the best conversion effect. Therefore, the HMF oxidation method has become the preferred method for preparing FDCA. The preparation of FDCA by HMF oxidation can be achieved through methods such as thermal catalysis, electro - chemical catalysis, photocatalysis and biocatalysis. Among them, the electro - chemical catalysis method has become the main method for green and efficient preparation of FDCA due to its advantages such as simple operation, controllable reaction, wide substrate selectivity and high safety. Electro - catalytic oxidation of HMF drives electron transfer with the anode potential, promotes the continuous oxidation of HMF, and finally converts it into FDCA. However, this process is often accompanied by the generation of intermediate products such as 2,5 - furandicarbaldehyde (DFF), 5 - formyl - 2 - furancarboxylic acid (FFCA) and 5 - hydroxymethyl - 2 - furancarboxylic acid (HMFFCA), etc. Therefore, optimizing and screening catalysts with strong selectivity, high activity and good stability is crucial for improving the reaction process of electro - oxidizing HMF. Nickel - based catalysts have advantages such as rich reserves, low price and adjustable structure, and have high application value in the field of electro - oxidizing HMF.

[0004] In view of this, the present invention provides a method for preparing a core-shell Ni@Ni3S2 catalyst for electro-oxidation of HMF to synthesize FDCA with a simple process and at a gram level, wherein the method only requires soaking nickel powder in a sodium sulfide solution to cause self-corrosion, and reacting at room temperature for 24 hours to form a nano-flower-shaped core-shell Ni@Ni3S2 catalyst. This method has the outstanding advantages of being simple and easy to operate, being able to achieve mass production at a gram level or above, being highly controllable, having low energy consumption, and being low cost. The Ni@Ni3S2 catalyst prepared by the present invention has high catalytic activity and high FDCA selectivity, is cheap and readily available, and can promote the efficient oxidation of HMF to prepare FDCA under mild conditions. Therefore, the present invention has broad market application prospects and commercial potential. Summary of the invention

[0005] The technical problem solved by the present invention is to provide a method for preparing a core-shell Ni@Ni3S2 catalyst for electro-oxidation of 5-hydroxymethylfurfural at the gram level with simple process and low cost. The method only requires immersing nickel powder in a sodium sulfide solution and undergoing a self-corrosion reaction at room temperature to obtain the catalyst. In addition to applying stirring to promote the reaction process, no other energy consumption is required, and a preparation scale of more than the gram level can be achieved, which has the advantages of low energy consumption and high industrial application potential. The present invention in situ grows an electro-oxidation HMF active shell on the surface of the nickel powder, and the prepared Ni@Ni3S2 catalyst with a nanoflower-like core-shell structure can effectively promote the electro-oxidation HMF reaction to prepare FDCA.

[0006] The present invention adopts the following technical solution to solve the above technical problems, a method for preparing a core-shell Ni@Ni3S2 catalyst for electro-oxidation of 5-hydroxymethylfurfural at a gram level, characterized in that the specific process is:

[0007] Step S1: ultrasonically clean the nickel powder using ethanol and deionized water in sequence to remove organic pollutants and other impurities on its surface, and obtain material A after cleaning;

[0008] Step S2: dissolving sodium sulfide in deionized water and mixing thoroughly to obtain solution B;

[0009] Step S3: placing the material A obtained in step S1 into the solution B obtained in step S2, stirring and reacting at room temperature, taking out the material A after the reaction stops, washing it with deionized water, and drying it to obtain the target product C, i.e., the core-shell structure Ni@Ni3S2 catalyst.

[0010] It is further defined that the nickel powder in step S1 is high-purity nickel powder with a particle size of 50-1000 nm.

[0011] It is further defined that the nickel powder in step S1 is ultrasonicated once in ethanol for 3 to 5 minutes; and is ultrasonicated twice in deionized water for 3 to 5 minutes respectively.

[0012] It is further defined that the molar concentration of sodium sulfide in step S2 is 30-50 mM.

[0013] It is further defined that the stirring in step S3 is mechanical stirring, the stirring reaction time at room temperature is 20 to 28 hours, the drying temperature is 60 to 90° C., and the drying time is 1 to 3 hours.

[0014] It is further defined that the method for preparing a core-shell Ni@Ni3S2 catalyst for electro-oxidation of 5-hydroxymethylfurfural at the gram level is characterized by the specific steps of:

[0015] Step S1: 50 mg of nickel powder was ultrasonically cleaned with ethanol and deionized water in sequence to remove organic pollutants and other impurities on its surface, and material A was obtained after cleaning;

[0016] Step S2: dissolving sodium sulfide in 30 mL of deionized water and mixing thoroughly to obtain a solution B with a concentration of 40 mM;

[0017] Step S3: placing the material A obtained in step S1 into the solution B obtained in step S2, stirring and reacting at room temperature for 24 hours, taking out the material A after the reaction stops, washing it with deionized water, and drying it to obtain the target product C, i.e., the core-shell structure Ni@Ni3S2 catalyst;

[0018] Step S4: The Ni@Ni3S2 catalyst obtained in step S3 is a nickel sulfide shell in situ grown on the surface of the metal nickel particles, and the nickel sulfide shell has a nanoflower-like structure. This core-shell structure can provide a large specific surface area and abundant active sites for the electrocatalytic reaction. The thickness of the nickel sulfide shell and the particle size of the nickel particle core can be controlled and adjusted by controlling the experimental conditions. The synergistic effect between the two can significantly improve the catalytic effect of the Ni@Ni3S2 catalyst. The Ni@Ni3S2 catalyst has a conversion rate of up to 98.32%, a 2,5-furandicarboxylic acid yield of 97.05%, and a Faraday efficiency of 98.13% during the HMF electrocatalytic oxidation process.

[0019] The core-shell structure Ni@Ni3S2 catalyst of the present invention is used as a working electrode to form a three-electrode system to realize the electrocatalytic oxidation of 5-hydroxymethylfurfural to synthesize 2,5-furandicarboxylic acid in an alkaline electrolyte.

[0020] It is further defined that in the three-electrode system, the platinum sheet and the mercury / mercury oxide electrode are the counter electrode and the reference electrode, the alkaline electrolyte is a 1 mol / L KOH solution or a NaOH solution, the concentration of 5-hydroxymethylfurfural dissolved is 5-100 mmol / L, the applied external potential is 1.35-1.6 V, and the core-shell structured Ni@Ni3S2 catalyst highly selectively electrocatalytically oxidizes 5-hydroxymethylfurfural in the alkaline electrolyte to prepare 2,5-furandicarboxylic acid.

[0021] The present invention has the following advantages and beneficial effects compared with the prior art:

[0022] 1. The preparation process of the core-shell structured Ni@Ni3S2 catalyst involved in the present invention is simple. The target product can be obtained through the self-corrosion of metallic nickel powder in sodium sulfide solution, and the preparation scale of gram level and above can be easily achieved. In addition, the preparation process is carried out at room temperature. Except for applying stirring to promote the reaction, there is no additional energy loss, and it has high potential for industrial production.

[0023] 2. The performance of the core-shell structured Ni@Ni3S2 catalyst involved in the present invention is comprehensively determined by the morphological structure of the Ni3S2 active layer shell and the thickness of the metallic Ni core. Moreover, the morphological structure of the shell and the grain size of the core are controllable. The Ni3S2 active layer shell is formed by the self-corrosion of the metallic nickel surface in sodium sulfide solution. Therefore, by regulating the solution concentration and reaction time, the effective control of the core-shell thickness and the shell morphology of the catalyst can be realized, so that the structure and performance of the catalyst have stronger controllability.

[0024] 3. The core-shell structured Ni@Ni3S2 catalyst involved in the present invention has a core-shell structure. The Ni3S2 active layer shell is helpful for the selective oxidation of HMF, and the active layer shell has a nano-flower-like structure, which can provide a large number of HMF oxidation active sites. The metallic Ni core can enhance the electrical conductivity of the catalyst and produce a synergistic effect with the active layer shell, further improving the catalytic performance.

[0025] 4. The high-efficiency electrocatalyst prepared by the present invention has a high oxidation current density of 56.02 mA cm at an overpotential of 1.45 V. The optimal catalyst has a HMF conversion rate of 98.32%, a FDCA yield of 97.05%, and a Faraday efficiency of 98.13%. -2 Description of the Drawings

[0026] Figure 1 X-ray diffraction patterns of products C1 and C9 prepared in Example 1 and Comparative Example 8;

[0027] Figure 2 Scanning electron microscope image of product C1 prepared in Example 1;

[0028] Figure 3 Scanning electron microscope image of product C9 prepared in Comparative Example 8;

[0029] Figure 4 Linear sweep voltammogram of HMF oxidation of products C1 - C4 prepared in Example 1 and Comparative Examples 1 - 3;

[0030] Figure 5 ​Linear sweep voltammograms of the products C1, C5 - C6 prepared in Example 1 and Comparative Examples 4 - 5 for HMF oxidation;

[0031] Figure 6 Linear sweep voltammograms of the products C1, C2, C7 - C8 prepared in Example 1 and Comparative Examples 1, 6 - 7 for HMF oxidation;

[0032] Figure 7 Electrochemical impedance diagrams of the products C1 and C9 prepared in Example 1 and Comparative Example 8;

[0033] Figure 8 Linear sweep voltammograms of the product C1 prepared in Example 1 for HMF oxidation and oxygen evolution;

[0034] Figure 9 Sample diagram of the product C1 prepared in Example 1 supported on the surface of carbon paper;

[0035] Figure 10 High - performance liquid chromatography analysis diagram of the products during the oxidation process of the product C1 prepared in Example 1;

[0036] Figure 11 Sample diagram of the product C1 prepared in Example 1 for gram - scale preparation. Detailed implementation mode

[0037] The following further elaborates on the above - mentioned content of the present invention through examples, but it should not be understood that the scope of the above - mentioned subject matter of the present invention is limited to the following examples. All technologies implemented based on the above - mentioned content of the present invention belong to the scope of the present invention. Example

[0038] Step S1: Weigh 50 mg of nickel powder, ultrasonicate it in ethanol for 3 - 5 minutes, and then ultrasonicate it in deionized water twice, each time for 3 - 5 minutes, to obtain material A1;

[0039] Step S2: Dissolve sodium sulfide in 30 mL of deionized water, and stir evenly to obtain solution B1 with a concentration of 40 mM;

[0040] Step S3: Put the material A1 in step S1 into the solution B1 in step S2, react at room temperature for 24 hours, stir once every 4 h during this period with a glass rod, wash the product A1 after the reaction with deionized water and ethanol, and then dry it in a blast drying oven at 80 °C for 2 hours to obtain the target product C1.

[0041] Comparative Example 1

[0042] Step S1: Weigh 50 mg of nickel powder, ultrasonicate it in ethanol for 3 - 5 minutes, and then ultrasonicate it in deionized water twice, each time for 3 - 5 minutes, to obtain material A2;

[0043] Step S2: Weigh 30 mL of deionized water and label it as solution B2;

[0044] Step S3: Put the material A2 in Step S1 into the solution B2 in Step S2, react at room temperature for 24 hours, stir with a glass rod once every 4 hours during this period, wash the product A2 after the reaction with deionized water and ethanol, and then dry it in a blast drying oven at 80 °C for 2 hours to obtain product C2.

[0045] Comparative Example 2

[0046] Step S1: Weigh 50 mg of nickel powder, ultrasonicate it in ethanol for 3 - 5 minutes, and then ultrasonicate it in deionized water twice, 3 - 5 minutes each time, to obtain material A3;

[0047] Step S2: Dissolve 20 mM of sodium sulfide in 30 mL of deionized water, stir evenly to obtain solution B3;

[0048] Step S3: Put the material A3 in Step S1 into the solution B3 in Step S2, react at room temperature for 24 hours, stir with a glass rod once every 4 hours during this period. Wash the product A3 after the reaction with deionized water and ethanol, and then dry it in a blast drying oven at 80 °C for 2 hours to obtain product C3.

[0049] Comparative Example 3

[0050] Step S1: Weigh 50 mg of nickel powder, ultrasonicate it in ethanol for 3 - 5 minutes, and then ultrasonicate it in deionized water twice, 3 - 5 minutes each time, to obtain material A4;

[0051] Step S2: Dissolve sodium sulfide in 30 mL of deionized water, stir evenly to obtain a solution B4 with a concentration of 60 mM;

[0052] Step S3: Put the material A4 in Step S1 into the solution B4 in Step S2, react at room temperature for 24 hours, stir with a glass rod once every 4 hours during this period. Wash the product A4 after the reaction with deionized water and ethanol, and then dry it in a blast drying oven at 80 °C for 2 hours to obtain product C4.

[0053] Comparative Example 4

[0054] Step S1: Weigh 50 mg of nickel powder, ultrasonicate it in ethanol for 3 - 5 minutes, and then ultrasonicate it in deionized water twice, 3 - 5 minutes each time, to obtain material A5;

[0055] Step S2: Dissolve sodium sulfide in 30 mL of deionized water, stir evenly to obtain a solution B5 with a concentration of 40 mM;

[0056] Step S3: Put the material A5 in Step S1 into the solution B5 in Step S2, react at room temperature for 12 hours, stir with a glass rod once every 4 hours during the reaction, wash the product A5 after the reaction with deionized water and ethanol, and then dry it in a blast drying oven at 80 °C for 2 hours to obtain the product C5.

[0057] Comparative Example 5

[0058] Step S1: Weigh 50 mg of nickel powder, ultrasonicate it in ethanol for 3 - 5 minutes, and then ultrasonicate it twice in deionized water, each time for 3 - 5 minutes, to obtain the material A6;

[0059] Step S2: Dissolve sodium sulfide in 30 mL of deionized water, stir evenly to obtain a solution B6 with a concentration of 40 mM;

[0060] Step S3: Put the material A6 in Step S1 into the solution B6 in Step S2, react at room temperature for 36 hours, stir with a glass rod once every 4 hours during the reaction, wash the product A6 after the reaction with deionized water and ethanol, and then dry it in a blast drying oven at 80 °C for 2 hours to obtain the product C6.

[0061] Comparative Example 6

[0062] Step S1: Weigh 50 mg of nickel powder, ultrasonicate it in ethanol for 3 - 5 minutes, and then ultrasonicate it twice in deionized water, each time for 3 - 5 minutes, to obtain the material A7;

[0063] Step S2: Dissolve sodium chloride in 30 mL of deionized water, stir evenly to obtain a solution B7 with a concentration of 40 mM;

[0064] Step S3: Put the material A7 in Step S1 into the solution B7 in Step S2, react at room temperature for 24 hours, stir with a glass rod once every 4 hours during the reaction, wash the product A7 after the reaction with deionized water and ethanol, and then dry it in a blast drying oven at 80 °C for 2 hours to obtain the product C7.

[0065] Comparative Example 7

[0066] Step S1: Weigh 50 mg of nickel powder, ultrasonicate it in ethanol for 3 - 5 minutes, and then ultrasonicate it twice in deionized water, each time for 3 - 5 minutes, to obtain the material A8;

[0067] Step S2: Dissolve sodium sulfate in 30 mL of deionized water, stir evenly to obtain a solution B8 with a concentration of 40 mM;

[0068] Step S3: Put the material A8 in Step S1 into the solution B8 in Step S2, react at room temperature for 24 hours, stir once every 4 hours with a glass rod during the reaction, wash the product A8 after the reaction with deionized water and ethanol, and then dry it in a blast drying oven at 80 °C for 2 hours to obtain the product C8.

[0069] Comparative Example 8

[0070] Step S1: Weigh 50 mg of nickel powder and ultrasonicate it in ethanol for 3 - 5 minutes to obtain the material A9;

[0071] Step S2: Put it into deionized water and ultrasonicate twice, 3 - 5 minutes each time, to obtain the material B9;

[0072] Step S3: Dry the material B9 in Step S2 in a blast drying oven at 80 °C for 2 hours to obtain the product C9.

[0073] Electrochemical performance test of electro - oxidizing HMF:

[0074] Use an H - type electrolytic cell to assemble a three - electrode system, separate it with a proton exchange membrane (Nafion - 117, DuPont). Mix 10 mg of the product C1, 5 mg of conductive carbon black, 0.06 mL of Nafion solution and 0.94 mL of deionized water evenly to obtain the catalyst slurry. Cut the carbon paper into 1 * 2 cm 2 size, use PTFE tape to isolate an effective area of 1 * 1 cm 2 dimension. Under a baking lamp, drop the evenly mixed catalyst slurry on both the front and back sides of the effective area of the carbon paper, 0.1 mL each time, 3 times in total. After the catalyst slurry loaded on both sides of the carbon paper is dried, use the carbon paper loaded with the catalyst as the working electrode. The mercury / mercuric oxide electrode and the platinum sheet (effective area 1 * 1 cm 2 ) electrode are used as the reference electrode and the counter electrode respectively. Insert the working electrode and the reference electrode into the anodic chamber, insert the counter electrode into the cathodic chamber, add 30 mL of 1 M KOH solution to both the anodic chamber and the cathodic chamber, and add 10 mM HMF additionally to the anodic chamber. Add a magnetic stirrer to the anodic chamber. When performing the electrochemical test, stir the anode to promote the mass transfer process. The scanning speed of the linear sweep voltammetry (LSV) test is 5 mV s –1 , the scanning range is 1 - 1.8 V (vs. RHE), and measure the impedance of the product at 1.45 V (vs. RHE).

[0075] Structure and performance analysis of the prepared catalyst:

[0076] The performance characterizations of the products in all examples and comparative examples are as follows: Figure 1X-ray diffraction patterns of products C2 and C9 prepared in Example 1 and Comparative Example 8 show that product C1 not only has characteristic peaks of Ni, but also has characteristic peaks of Ni3S2, proving the formation of a Ni3S2 active layer on the surface of product C1. Figure 2 Scanning electron microscopy image of product C1 prepared in Example 1 shows that product C1 has a structure with a nanoflower-like outer shell. Combining with the X-ray diffraction pattern, it can be proved that the surface nanoflower-like outer shell is Ni3S2 and the inner core is metallic nickel. Figure 3 Scanning electron microscopy image of product C9 prepared in Comparative Example 8 shows that product C9 has a spherical structure with a smooth surface. Figure 4 Linear sweep voltammograms of products C1 - C4 prepared in Example 1 and Comparative Examples 1 - 3. It can be seen from the figure that product C1 has a lower initial potential and a higher current density compared with other products, indicating that product C1 with a sodium sulfide solution concentration of 40 mM has better performance in HMF oxidation compared with products C2 - C4 with other concentrations. Figure 5 Linear sweep voltammograms of products C1, C5 - C6 prepared in Example 1 and Comparative Examples 4 - 5. It can be seen from the figure that product C1 with a reaction time of 24 h has better performance in HMF oxidation compared with products C5 - C6 with different reaction times. Figure 6 Linear sweep voltammograms of products C1, C2, C7 - C8 prepared in Example 1 and Comparative Examples 1, 6 - 7. It can be seen from the figure that product C1 with a reaction solution of sodium sulfide has better performance in HMF oxidation compared with other products C2, C7 - C8. Figure 7 Electrochemical impedance spectra of products C1 and C9 prepared in Example 1 and Comparative Example 8. The radius of product C1 is smaller, indicating that product C1 has a lower interfacial charge transfer resistance, which is helpful for charge transfer during HMF oxidation. Figure 8 Polarization curves of HMF oxidation and oxygen evolution of product C1 prepared in Example 1. The figure shows that the initial potentials of product C1 in the processes of HMF oxidation and oxygen evolution are similar, but the oxidation current density in the HMF oxidation process is higher than that in the oxygen evolution reaction. When the current density is 50 mA cm –2 At this time, the overpotential of HMF oxidation of product C1 is 205 mV lower than the oxygen evolution potential, indicating that product C1 is more inclined to undergo HMF oxidation reaction at this time. Figure 9 Schematic diagram of the working electrode formed by loading the slurry formed by mixing product C1 prepared in Example 1 with conductive carbon black, Nafion solution and deionized water onto a carbon paper with an effective area of 1 * 1 cm 2 2. Figure 10The figure shows the oxide changes of the product C1 prepared in Example 1 during the electrooxidation of HMF to FDCA. The figure shows that there are mainly two substances, HMF and FDCA, during the oxidation process. This indicates that after HMF is oxidized to an intermediate product, it will be rapidly converted to FDCA. The HMF conversion rate of 98.32% and the FDCA yield of 97.05% indicate that the catalyst has excellent catalytic performance.

[0077] The above embodiments describe the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited by the above embodiments. What is described in the above embodiments and the specification only illustrates the principles of the present invention. Without departing from the scope of the principles of the present invention, the present invention will have various changes and improvements, and these changes and improvements all fall within the scope of protection of the present invention.

Claims

1. A method for preparing a core-shell structured Ni@Ni3S2 catalyst for electro-oxidizing 5-hydroxymethylfurfural on a gram scale, characterized in that The specific steps are: Step S1: 50 mg of nickel powder is ultrasonically cleaned with ethanol and deionized water in sequence to remove organic pollutants and other impurities on its surface, and material A is obtained after cleaning. The nickel powder is high-purity nickel powder with a particle size of 50-1000 nm; Step S2: dissolving sodium sulfide in 30 mL of deionized water and mixing thoroughly to obtain a solution B with a concentration of 40 mM; Step S3: placing the material A obtained in step S1 into the solution B obtained in step S2, stirring and reacting at room temperature for 24 hours, taking out the material A after the reaction stops, washing it with deionized water, and drying it to obtain the target product C, i.e., the core-shell structure Ni@Ni3S2 catalyst; Step S4: The Ni@Ni3S2 catalyst obtained in step S3 is a nickel sulfide shell in situ grown on the surface of the metal nickel particles, and the nickel sulfide shell has a nanoflower-like structure. This core-shell structure can provide a large specific surface area and abundant active sites for the electrocatalytic reaction. The thickness of the nickel sulfide shell and the particle size of the nickel particle core can be controlled and adjusted by controlling the experimental conditions. The synergistic effect between the two can significantly improve the catalytic effect of the Ni@Ni3S2 catalyst. The Ni@Ni3S2 catalyst has a conversion rate of up to 98.32%, a 2,5-furandicarboxylic acid yield of 97.05%, and a Faraday efficiency of 98.13% during the HMF electrocatalytic oxidation process.

2. The core-shell structure Ni@Ni3S2 catalyst prepared according to the method of claim 1 is used as a working electrode to form a three-electrode system to realize the electrocatalytic oxidation of 5-hydroxymethylfurfural to synthesize 2,5-furandicarboxylic acid in an alkaline electrolyte.

3. The application according to claim 2, characterized in that: In the three-electrode system, a platinum sheet and a mercury / mercury oxide electrode are used as a counter electrode and a reference electrode, an alkaline electrolyte is a 1 mol / L KOH solution or a NaOH solution, a concentration of 5-hydroxymethylfurfural is 5-100 mmol / L, an applied potential is 1.35-1.6 V, and a core-shell structured Ni@Ni3S2 catalyst can electrocatalytically oxidize 5-hydroxymethylfurfural in an alkaline electrolyte to prepare 2,5-furandicarboxylic acid with high selectivity.

Images